[Nexus 5 Accessories] EdZ:
Just picked up an MW600 from ebay, though I'd give it a quick review.

What you get:

The bluetooth receiver itself

A pair of in-ear headphones (IEMs/Canalphones), with a very short cable as the receiver is intended to clip to a collar, lapel or pocket

- With 3 sets of rubber earbuds, small medium and large

A micro-USB charger

As a bluetooth headset:

It works. You can hear people talk, people can hear you (the microphone is on the receiver). You can answer calls with the call button, and hang up with the same button. Slight annoyance: the Nexus 5's speaker will play the your ringtone even when the headset is connected, which for many may be unnecessary. This seems to be an android issue rather than with the headset itself. If someone know the setting to turn this off, I'd appreciate it.

As a pair of bluetooth headphones:

Actually rather good for a headset released in 2009, so pre-aptX. The included earbuds are of entirely acceptable sound quality, but you can swap them with headphones of your choice as the receiver accepts anything with a 3.5" minijack/TRS. It'll even drive my big Sennheiser 555 cans quite happily, so unless you have something with a monstrous impedance you're good. There's a slight hiss noticeable occasionally (mainly during quiet sections with loud beats, or other situations with a very wide dynamic range) due to the older SBC codec. Personally I'm happily switching to these from my UE700s for the added convenience. You can easily hit 100% volume without any audible distortion or clipping. Only real complaint is that in shortening the headphone lead, the receiver pretty much has to be clipped to your collar or pocket, so it's not long enough to hold comfortably in your hand.

The display:

It works! No configuration needed, the track title shows up there automatically. A basic monochrome OLED, it's bright enough to see but nothing fancy. Will show track name when playing, call time when in a call, and current volume level when using the volume slider. The display will fade after 2-3 seconds without touching any controls, and pressing any control (or tapping the volume slider without sliding along it) will bring it back on.

Battery life:

Enough for 3+ hours of commuting a day. I keep them topped so so I haven't run them down yet, but other reviews have clocked them between 8 and 10 hours of battery life.

The controls:

Button for pickup/hangup on the front, next to the display. Power button on the base next to the micro-USB port. Previous track/play-pause/next track buttons on one side, volume slider on the other. The volume slider IS a bit fiddly being touch-sensitive, but you can get used to it. Sliding up and down works 1:1 over subset of the total volume range (e.g. swipe from the bottom to the top from 0 volume you get you to 50%, swiping from button to top again would get you to 100%), and holding at either end where the raised symbols are will act like holding down the volume rocker does. You won't accidentally touch the wrong end of the slider and get blasted with full volume.

Images (click for full size):

Summary:

They work surprisingly well, they're old so going cheap, and you probably want to spend the extra £2 and opt for the black model. Well worth the £27 I paid for them.